New shed roof covering

[campbela]

The felt roof covering on my shed appears to be leaking. The shed was build by the supplier in 2018 so its only lasted 6 years - I was expecting a bit of a longer life out of the roof covering but then I dont know what quality it is.

I have been looking around at shed roof coverings and come up with the following options:

1) Replace with felt (thicker/better quality) 2) Replace with a rubber/EPDM covering 3) Replace with bitumen corrugated sheets

I have done option 1 before on a previous shed and I am comfortable with what is required.

Does anyone have any experience with either option 2 or 3? Are they worth the extra money? Do they last a lot longer?

Thanks

Alan

[Andy Burns]

I've used 2) on a garage roof, the ruber itself is fine, but the fixing system round the edges is not holding up well after ~12 years, hoping I can re-do that over the summer ...

I've used 3) on my shed, and would do it again with zero hesitation, about 10 years down and no signs of wear at all.

[John Rumm]

If you go for a 2 layer "torch on" felt with a under layer and a cap sheet, then that will do 20 years easily. It is also very quick and easy to apply but you will need a big blowtorch.

Possibly excessive for a shed

Would also work can can be fairly quick and easy.

To be fair, anything will last better than your typical "shed grade" felt - especially if it was only a single layer and was just nailed on.

[alan_m]

With some of the cheap stuff it cracks rather than bends if you try and install it at any temperature below 30C. :)

[John Rumm]

Which in the UK limits it to a two week window in June sometime! :-)

[SteveW]

I re-covered my shed with box section steel roofing a few years ago, after the felt failed yet again. This was the solution that I applied to my garage about 15 years ago and which is still going strong - in fact, I am going to widen and lengthen my garage (concrete panel construction) and will be re-using the existing roofing for a big chunk of it.

[nothanks]

Yes, that's what I've done on a shed with a tired felt roof. It's a simple job to fit it over the existing felt using tek screws - assuming the board is sound, of course.

[me9]

Used option 2 a few years back, Had to replace boards with OSB first. Job should see me out. (nearly finished me off, I nearly slipped off teh roof grabbing the pot of glue which was sliding down!)

It was more expensive than felt but easier to fit and is as good as new now, after about 5 years.

[campbela]

Do you have any recommendations for some "decent stuff"?

Thanks

[Tim Lamb]

I have used Wickes heavy grade mineralised felt on stables.

The trick is to lay and lap the felt *up* rather than *along* the roof pitch. Use treated softwood battens for the laps and midway securing. Soften the felt with a hot air blower to form the eaves drip and secure with flat head galvanised nails. Ideally the ridge needs to be galvanised steel but you can repeat the heated/fold/nail job for a shorter life.

[Adam Funk]

That's what I have on my shed too. I think I built the shed in 2008 or so and put corrugated translucent panels from Wickes on it, but they eventually became delicate (from sunlight, I assume) and got a couple of holes from bumping the roof while putting a ladder away.

I got box profile stuff from cladco.co.uk in spring 2020 and installed it, but it was relatively easy because I built the shed without a ridge. The roof just slopes down from front to back with a good overhang both ways.

[PeterC]

About 25 years ago I needed to refelt a duck house and a hen coop. Went to B&Q looke at the extra-strong felt - 2 fingers and a thumb just tore it. Wennt to a roofing merchant and bought glass-fibre felt (looked just the same but not tearable), No trouble when bending it in winter.

[John Rumm]

If looking at torch on ones, the ones with rubberised modifiers in the bituminous layer apply more easily and bond better, so typically something with SBS (Styrene-Butadiene-Styrene) or APP (Atactic Polypropylene) in the title.

I normally use a 4mm underlay, with a 2mm mineral finish cap sheet.

Brand is probably less important, but most of the ones carried by proper roofing stores and builder's merchants are likely to be fine.

[TimW]

After several refeltings and over-feltings I did onduline or equivalent bitumeny corrugated. NO MORE LEAKS! I think some movement in the cheap and flimsy shed without foundations was tearing the felt. Onduline easy to install, over the top of the felt if you want. Life-span 15-20 yrs I believe.

TW

[Andrew]

And suppliers might have minimum order sizes.

Since it is a shed, EPDM pond liner is available in a variety of widths from some garden centres. It will be the thinner version of that intended for garages and flat roofs but ok for a shed.

getting hold of a smaller quantity of the special adhesive might be tricky though and the shed would need to be overcovered with 11mm OSB.

[Andy Burns]

I've seen suppliers doing "shed packs" of EPDM.

[Harry Bloomfield Esq]

4) Replace with box section, corrugated steel, galvanised, then colour coated. It will outlast all of the others, many times over.

[Harry Bloomfield Esq]

+1

I replaced my garage roof with it, originally, so pleased with it - I then did my workshop extension too. More recently, fed up of patching the summerhouse roof, last year I did that too with the steel.

[RJH]

OOI. how does it cope with being cut and drilled, rust wise?

[SteveW]

No problem at all. You can paint the cut edges with a galvanising paint, but it is unnecessary. The Galvanic protection is not just to the surface covered, but for a small distance beyond the covering - more distance than the thickness of the sheet - so even the cut edges remain protected.

There is still not a sign of any rust on my garage roof. I guessed at when I installed it before, but I've just checked on Google Earth and I put the galvanised steel on some time between 2005 and 2008.